Apparatus for grinding threaded work



Jan 26, 1932. J, H 1,842,650

APPARATUS FOR GRINDING THREADED WORK Filed Dec. 20, 1928 5 Sheets-Sheet 1 (75%;? E'afi,

Jam. 26, 1932. J. BATH 1,842,650

APPARATUS FOR GRINDING THREADED WORK Filed D60. 20, 1928 5 Sheets-Sheet 2 Jan. 26, 1932.. B 1,842,650

APPARATUS FOR GRINDING THREADED WORK Filed Dec. 20, 1928 5 Sheets-Sheet 3 1 325. 1&4.

J. BATH L KKW APPARATUS FOR GRINDING THREADED WORK Filed Dec. 20, 1928 5 Sheets-5heet 4 W H if? Patented James, 1932 UNITED STATES PATENT OFFICE JOHN BATH, F WORCESTER, MASSACHUSETTS APPARATUS FOR GRINDING THREADED WORK Application filed December 20, 1928. Serial No. 327,387..

to enact required section, and that the cuttin edge should he at all; times clean and o emloedded particles of metal. This result is most efi'ectively attained by accurately truing or dressing the wheel edge after each passage of the grinding wheel over the work.

lit is the general object of my invention to provide an improved combination, of grinding mechanism and wheel truing mechanism hy which the wheel may bedressed or trued as needed and by which it will be maintained in or will be restored to exact operative position with a minimum expenditure of time, and with no possibility of inaccurate setting or adjustment. Y 3 o More specifically, I provide improved means for simultaneously adjusting the grinding wheel and wheel truing device as a lid unit toward the work and also for advancing the wheel truing device relative to the grind W ing wheel, to the end that the cutting edge of the wheel maybe maintainedin the exact position necessary to produce the predeter-' Jmined diameter of finished work.

My invention further relates to arrangements and combinations of parts which will he hereinafter described and more particularly pointed out in the appended claims. u

A preferred form of the invention is shown in the drawings in which Fig. 1 is a plan view showing parts of a thread grinding machine embodying my improvements;

Fig. 2 is a rear elevation of looking inthe direction of thearrow 2 in Fig.1;

Fig. Sis a sectional side'eflevation, taken along the line 3-3 in Fig. 2';

Fig. 4 1G" a slde elevationg looking in the direction or the arrow 4 in Fig. 2';

these parts,

Fig. 5 is a detail plan view,'looking in the direction of the arrow 5 in Flg. 4;

Fig. 6 is a detail rear'view of an adjustable gear support;

Fig. 7 .is a side elev ation'of the support, 55 looking in the direction of the arrow 7 in Fig. 6; i I y ig. 8 is a diagrammatic view illustrating the operation of the mechanism shown in Figs. 1' to 7'; l to Fig. 9 is a partial plan view of a mod1fied construction;

- Fig. 10-is a partial end elevation thereof,

looking intli'e direction of the arrow 10 in F 7 Fig. 11 is a side view, looking in the direction of the arrow 11 in Fig. 9, and

Fig. 12 is a detail elevation of a work supporting structure. a I

Referring to the drawings, I have indicated portions of a thread grinding machine including a head stock'1 0 (Fig. 1) and a tail stock 11, provided with centers 12 and 13 on' which the work W is supported. The workis preferably provided with a dog Meengaged by a driver 15 rotating with the work spindle 16 in the head stock 10. a

A grinding wheel G is mounted on'a wheel shaft 20, rotatable in a bearingfll formed on or secured to a wheel slide 22. T e slide so 22 (Fig. 2.) is moiinted for movement for: ward and rearward on guide ways 23 and. 24 on a wheel table 26,sl1dable' axially of the wheel and longitudinally of the machine on a'base or frame 27. 85

Suitable mechanism (not shown) is provided for rotating thegrindin wheel G and the work spindle 16 and for fee ing the wheel table 26*jlongitudinally to produce the necessary travel of the wheel relative to the work to grind a thread of the desired pitch. The mechanism for. driving the wheel and the work and the table feeding mechanism in themselves form no part of my present invenbe of any usual or desired cont cs tion and may struction.

Wheel feeding For feeding the wheel G toward or away from the work W,"'I"have provided a hand 1:5

wheel (Fi 1) mounted at the front end of a feed sha 31 rotatable in fixed bearings 32 and 33 on the wheel slide 22. A disc or dial 34 is rotatable with the hand wheel 30 and shaft 31, and may be provided with suitable graduations 35 cooperating with an index mark (not shown) to indicate the exact amount of wheel feed. I

A worm 36 is secured to. the rear end of the shaft31 and engages a worm wheel 37 mounted at the upper end of a substantially vertical shaft 38 (Fig. 2). The shaft 38 is rotatable in bearings 39 and 40 on a brack-' et 41 secured to an upward projection 22 of the wheel slide 22. The shaft 38 is also provided with a lower bearing 41 secured directl to the wheel slide 22.

A evel pinion 42 is mounted on the lower end of the shaft 38 and engages a bevel gear 43 (Fig; 3) secured to the rear end of a lead screw shaft 44 mounted for rotation in a bearing 45 fixed to a depending portion 46 of the wheel slide 22. The shaft 44 is held from relative axial movement in the bearing 45 b a flange or collar 47 at one end of the bearing and by the hub of the bevel gear 43 at the other end of the hearing.

The lead screw 50 of the shaft 44 is threaded into a nut 51, mounted in a bracket 52 secured to the rear edge of the wheel table 26. The nut 51 may be made in two parts, as indicated in Fig. 3, with one of the parts threaded in the bracket 52 and held in adjusted position by a lock nut 53. By relatively adjusting the-two portions of the nut all backlash or wear may be eliminated.

As the hand wheel 30 is turned, the lead screw 50 will be caused to rotate in the nut 51 fixed on the wheel table 26, thus causing forward or rearward movement of the lead screw and of the wheel slide 22 positioned thereby.

Tmz'ng nwclzam'sm For truing the grinding wheel, I have provided a pair of diamond points or wheel dressing tools and 61 (Fig. 1) secured at the forward end of tool slides 62 and 63 mounted in guideways in stands 64 and 65 adjustably secured to a support or table 66. The table 66 is slidable in guideways 66 (Fig. 5) formed on a bracket 67 (Fig. 2) pro e cti1pg laterally from the wheel slide 22 'and manually adjustable forward and rearward on guideways thereon. The bracket is normally clamped in fixed position on the wheel slide.

The table 66 is also provided with a nut 68 fixed to the under side of the table and threaded to receive a feed screw 69 mounted for rotation in-a bearing 70 on the bracket 67 but held from axial movement in said hearing. The feed screw 69 is provided with a handle 71 by which it may be directly rotated for preliminary adjustment of the truing device, and is also provided with a gear 72 fixed to said feed screw and engaged by a train of adjusting mechanism to be described.

The dressing tool slide 62 (Fig. 1) is connected by a link 75 to a stud 76 on a threearmed lever 77 connected by a link 78 to a stud 79 in a crank disc 80-. The disc 80 is pivoted at 81 on the plate 82 bolted to the table 66 and is provided with an arm 83 having a pin and slot connection to a piston rod 84 actuated by a piston 85, slidable in a hydraulic cylinder 86 mounted on a bracket 87 secured to the plate 82.

Pipes 88 and 89 are provided for admitting oil under pressure to one side or the other of the piston 85, causing the piston to be reciprocated and rock the disc 80, which in turn causes the wheel dressing tool 60 to travel back and forth along the beveled edge of the grinding wheel. The details of constructimr of the hydraulic mechanism and the devices for controlling-said mechanism form no part of my present invention but are fully disclosed and claimed in the co-pending application of Stanley Bath, Serial No. 345.112. filed March 7, 1929.

The slide 63 for the second wheel dressing tool 61 is similarly connected by an adjustable three-piece link 90 to a stud 91 on the three-armed lever 77 and is thus simultaneously reciproeated with theslide 62 but in such a direction that the tool 60 will move toward the'edge of the wheel as the tool 61 is moving away from the wheel. In the usual operation of the machine, a single passage of the tools 60 and 61 is sufiicient to restore the exact desired cutting edge to the wheel G.

Tming device feeding mechanism,

I have provided positive operative connections between the lead screw 50 of the wheel slide 22 and the feed screw 69 of the truing device slide 66, by which a definite advance movement of the slide 66 is caused for every advance movement of the wheel slide 22.

For this purpose I provide tho upright shaft 38 (Fig. 2) with a bevel gear 100,- engaging a corresponding bevel gear 101 fixed to one end of a short shaft 102'rotatable in a bearing 103 on the bracket 41.

A clutch member 104 is mounted on the opposite end of the short shaft 102, projecting beyond the same and providing a hearing for one end of a second shaft 105 on which a clutch operating member 106 is slidable. The member 106 engages a clutch lever 107 by which the clutch member 104 is connected to an inner clutch member 108 fixed to the shaft 105.

The right hand end of the shaft 105 is rotatable in a bearing 110 on the bracket 41 and the shaft is provided with a bevelgear 111 engaging a pinion 112 (Fig. 4) mounted on a short shaft 113 rotatable in a bearing'114 mounted on an arm 120 (Figs.

- the end of a swinging arm 118 till 6 and 7) depending from the bracket 41. A gear 115 on thersha'ft 113 engagesa wide gear 116 mounted on a stud 117 secured in (Big. 6). The arn1118 is pivoted about the axis of the shaft 113 previously describedand has a bolt and slot"connection with the arm 120 which supports the bearing 114.. The widegear 116 meshes with a gear 72 on the feed screw 69 previously described. 1

The clutch member 106 is controlled by a yoke 122, pivoted at 123 (Fig. 1) and connected by a link 124 to a crank arm 125 on the rear end of a rod 126, mounted in bearings 127 on the wheel slide 22 and having a handle 128 at its front end. Theclutch mem her 106 is normally ,in the osition indicated in Fi 2, in'whlch positlon the clutch is tightened and connects the members-104 and 108, thus locking the short shaft 102 to the bevel gear shaft 105. The clutch is released by movement of the handle 128 only when it is desired to relatively adjust the 'truing device and wheel, as for instance when a new wheel is inserted, or to'eifect the slight wear of the diamond-points.

The machine has been thus far described as operated by manual turning of the hand wheel 30. In Fig. 1, however, I have indicated mechanism by which the truing device and grinding wheel may be fed forward by power, For this purpose a worm gear 130 (Fig. 1) is-loosely mounted on the shaft 31 and is continuously rotated by a worm 131 on a shaft' 132, driven from any convenient source of power through connections, not shown. The worm gear 130 is provided with clutch teeth 133, and a corresponding clutch member 134 is keyed on the shaft 31 and is slidable thereon, .into and out of operative engagement with the teeth 133. The clutch Metiwd of operation Having describedthe "construction of my improved grinding machine and truing mechanism,- the method of operation is as follows:

, Assume that the truingdevice has been manually, adjusted by. the handle 71 so that the edge of-the wheel G is properly formed and dressed and that the cutting edge is in the exact position relative to the work- W to e5 grind the workto the desired finished size.

After a single passage of the wheel along the vance movement being commonly only one or twothousandths of an inch. 1 i

As the wheel truing devices are mounted on the slide 66 which is in turn su ported by the wheel slide 22, the truing dhvices are advanced with the wheel, theadvance movement=being of exactly the same amount. At the same time, the feed screw for the truing device slide 66 isalso rotated an amount corresponding to the movement of the hand wheel 30, and the truing device slide is thus given an additional advance movement. The gearing between the feed shaft 31 and the feed screw 69 is so designed that the supplemental advance movement of. the truing device slide relative to the wheel slide is exactly equal to the initial advance movement of the grin d by theexact amount of the supplemental ad Vance of the truing device slide, this amount King also equal to the initial advance more out of the wheel toward the work.

The cutting edge of the wheel is thus restored to the exact position relative to the axis ofnthe work which it originallyoccupied, and a piece of work ground by the wheel in its new position will be of exactly thesame size as the work produced by the wheel in its old position and before the truing of the wheel.

If the operator advances the wheel one thousandth of an inch as indicated in Fig. 8,

the diamond points 60 and 61 will be advanced one thousandth of an inch with the wheel slide and will also be advanced an additional one thousandth of aninch relative to the wheel slide, making a total advancemovement of the diamond points of two thou sandths of an inch, while the wheel has been advanced only one thousandth. The diamond points will then reduce the radius of the wheel one thousandth of an inch, restoring the cutting edge to the original position relative to the axis of the wor If the wheel had been advanced tvyo thousandths of an inch, the. diamond points would have been automatically advanced four thousandths, thus producing the same final result? I am thus able to dress the wheel as often as may be necessary and at each dressing the cutting edge of the wheel 1s automatically maintained in itsi exact initial position. If, on account of wear 6f the diamond points or for any other. reason, the work is found to be slightly over-size, the clutch may be released by the handle 128 anda slight manual adj ustment of the diamond points may be made to bring the work to the exact reqiliredt di'- ameter. 1

In Figs. 9 to- 12, I have. indicated the adap tation of my invention to a machine for grinding thread dies or similar fiat grooved work. 1

In such machines the wheel is fed vertically downward toward the work and the truing devices are arranged to operate at the back side of the wheel, as in the form previously described.

Referring to the drawings, I have shown a hand wheel 150 mounted on a vertical feed screw 151 and having a graduated disc 152 (Fig. 11) rotatable therewith to indicate the amount by which the wheel G is fed downward. A ratchet 153 is secured on the shaft 151 and a suitable manuel or automatic feed mechanism is provided by which the shaft 151 may be rotated intermittently, each step corresponding to one or more teeth of the ratchet wheel. The details of the mechanism for feeding the wheel G vertically downward form no part of my present invention and need not be further described herein.

A gear 154 (Fig. 11) is secured on the shaft 151 and meshes with a small intermediate gear 154 which in turn engages a gear 155 on a telescoping upright shaft 156 rotatable in fixed bearings and having a bevel gear 157 at its lower end. The gear 157 meshes with a gear 158 on a short shaft 159 having a frictifon hub 160 extending beyond the end there- 0 A second short shaft 161 is rotatable in a recess of the hub 160 and is provided with a slidable member 162 positioned by a yoke 163 and engaging friction fingers 164 on the hub 160. The yoke 163 (Fig. 10) is mounted on a stud 165, rotatable in a fixed bearing 166, and having a shift lever 167 secured to the upper end thereof. The lever 167 is normally in forward position, causing the clutch members to engage and rotate the shafts 159 and 161 in unison.

A large gear 170 (Fig. 10) is mounted on the rear end of the shaft 161 and meshes with an intermediate gear 171 pivoted at 172 on an arm 17 3 adjustable about the axis of the shaft 161. The arm 173 may be secured in adjusted position by a clamping bolt 174, extending through a segment slot 175 in the arm 173. The intermediate gear 171 meshes with a second intermediate gear 176 also' mounted on the arm 173 and engaging a gear 178 fixed at the rear end of the feed screw 180. A handle 181 is also secured to the rear end of the feed screw 180 for manual rotation thereof when desired.

The truing devices may be of the construction' previously described and are mounted on a slide or table 185 (Fig. 9) supported on guideways 186 on the wheel head and having a nut 187 threaded on the feed screw 180.

With this construction it will be seen that downward movement of the wheel G by the feed screw151 will cause corresponding forward movement of the truing devices, and the truing device will be .fed forward the same exact amount that the grinding wheel is fed downward, while at the same time it also moves downward with the grinding wheel.

The mechanism shown in Figs. 9 to 11 is particularly adapted for truing and positioning a grinding wheel W used for grinding the grooves in the face of a thread die D such as is shown in Fig. 12, the die being secured on a table 190 and slidable on a support 191 in a horizontal plane beneath the grinding wheel G. j Having described two forms of my invention, it will be seen that I have provided improved mechanismfor keeping the V-shaped face of a thread grinding wheel accurately.

formed and for simultaneously maintaining the cutting edge of the wheel in a predeter-- mined positi0n,- so that the threads ground thereby will be of uniform depth and diameter.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is i 1. In a thread grinding machine, means to support and move the work, a grinding wheel,-

a wheel shaft, a bearing head for said wheel shaft, adjustable toward and from the work, a pair of wheel truing devices, a support on said bearing head in which said truing devices are slidable in angularly disposed paths to true and shape the wheel to grind the thread, means-tofeed said truing device support toward the wheel, and means positively connected to said first feeding means and effective to move the support and wheel as a unit an equal distance toward the work.

2. The combination in a thread grinding machine as set forth in claim 1 in which the feeding means is driven by direct gearing from'the wheel moving means, and in which automatic means is provided for actuating said feeding means and said wheel moving means continuously.

3. The combination in a thread grinding machine as setforth in claim 1 in which the feeding means is driven by direct gearing from the Wheel moving means, and in which means is provided at the front of the machine for manually disconnecting said truing device feeding means from said wheel moving means and permits independent actuation of said truing device feeding means.

4. In a thread grinding machine, means to support and move the work,'--a grinding wheel, a wheel shaft, a bearing head for said wheel shaft, adjustable toward and from the work, a pair of wheel truing devices, a support on said bearing head in which said truing devices are slidable in angularly disposed paths to true and sha e the wheel to grind the thread, means to eed said truing iii positively connected to said first feeding means and effective to move the support and Wheel as a unit an equal distance toward the work, and said truing device feeding means and said Wheel moving means being operable at any point in the travel of the Wheel relative to the work.

5. The combination in a thread grinding machine as set forth in claim 1, in which the feeding means is driven by direct gearing from the Wheel moving means, and in which automatic means is provided for actuating said feeding means and said wheel moving means continuously and in which the rate of movement of said automatic means is independent of the rate of rotation of the grinding Wheel and Work.

in testimony whereof I have hereunto aflixed my signature.

JOHN BATH. 

